Have ants in your pants- not be able to keep still because you are very excited or worried about something.
Having a whole of a time- to enjoy very much
Hold one’s horse- be patient
Have a big mouth- one who gossips more or tells secret
Himalayan blunder- a serious mistake
Have a one track mind- think only of one thing
Have clean hands- be guiltless
Have an egg on the face- be embarrassed
Have eyes bigger than stomach- desiring more food than one can eat
Heart missed a beat- very excited
Heart in the right place- good natured
Hit the nail on the head- done the thing correctly
Hand to mouth- Someone who's living from hand to mouth, is very poor and needs the little money they have coming in to cover their expenses
Have no truck with- If you have no truck with something or someone, you refuse to get involved with it or them
Hit the bull's-eye- If someone hits the bull's-eye, they are exactly right about something or achieve the best result possible.
Hold water- When you say that something does or does not 'hold water', it means that the point of view or argument put forward is or is not sound, strong or logical. For e.g. 'Saying we should increase our interest rates because everyone else is doing so will not hold water'
Hornets' nest- A hornets' nest is a violent situation or one with a lot of dispute. (If you create the problem, you 'stir up a hornets' nest'.)